1. Field of the Invention
The present invention relates to a method for fabricating a chip type solid electrolytic capacitor and an apparatus for performing the same method, and more particularly to a welding method for connecting an anode terminal and an anode lead of the solid electrolytic capacitor.
2. Description of the Prior Art
An example of a conventional method for fabricating a chip type solid electrolytic capacitor, which may be referred to as merely xe2x80x9cchip type capacitorxe2x80x9d sometimes in this description, is disclosed in Japanese Patent No. 3084895. The fabrication method of chip type capacitor disclosed therein includes the step of putting an anode lead extending from a capacitor element on a connecting portion, which is formed by bending up a portion of the anode terminal, and the step of welding the connecting portion and the anode lead together by laser light.
However, since, in the conventional method, the connecting portion and the anode lead are positioned relatively with loose contact of them and welded together by laser light, there may be a case where the anode lead cannot be in sufficient area contact with the connecting portion during the welding operation. If the welding is performed in such state, there is a problem that a sufficient bonding strength cannot be obtained and, as a result, the quality of a chip type capacitor is degraded.
Further, in the disclosed conventional fabrication method, there may be a case where, in welding the anode lead and the connecting portion together by laser light, the laser light may be reflected by a weld portion and reflected laser light may irradiate other portion of the capacitor element undesirably. Particularly, when the reflected laser light irradiates the capacitor body of the capacitor element, a problem that the quality of the capacitor body and hence the chip type capacitor is degraded occurs.
The present invention was made in view of the state of the prior art and has an object to provide a method for fabricating a high quality chip type solid electrolytic capacitor and a fabrication apparatus for performing the same fabrication method.
In order to achieve the above-mentioned object, a fabrication method of a chip type solid electrolytic capacitor, according to a first aspect of the present invention, is featured by comprising the steps of putting an anode lead, which extends from a capacitor body of a capacitor element of the chip type solid electrolytic capacitor on a connecting portion, which is formed by bending a portion of an anode terminal and welding portions of the connecting portion and the anode lead together with using laser light while the anode lead is urged to the connecting portion in a region between the weld portion of the connecting portion and the capacitor body.
Since the laser light welding operation is performed while the anode lead is urged to the connecting portion, it is possible to always perform the welding operation while the anode lead is in firm contact with the connecting portion. Therefore, degradation of bonding strength can be avoided.
Consequently, it is possible to obtain a high quality chip type solid electrolytic capacitor.
Further, since the anode lead is pressingly held between the weld portion and the capacitor body, it is possible to improve the freedom of irradiating direction of laser light. On the other hand, it has been known in the fabrication of chip type solid electrolytic capacitors that a plurality of capacitor bodies bonded to a metal plate of such as aluminum, which may be referred to as xe2x80x9caluminum holderxe2x80x9d, are processed through respective fabrication steps. In such case, anode leads thereof are not in one and the same horizontal plane due to bending or warping of the bonding portions of the anode leads to the aluminum holder and, therefore, the contacting state of the anode leads with the connecting portions is unstable. In the present invention, when the pressing force is selected to a value enough to correct such bending and/or warping of the anode lead, the bending and/or warping of the anode lead can be corrected, so that the welding operation can be performed in the state where the anode lead is always in firm contact with the connecting portion.
A fabrication method for fabricating a chip type capacitor, according to a second aspect of the present invention, including the step of mounting an anode lead extending from a capacitor body of a capacitor element on a connecting portion formed by bending up a portion of an anode terminal and welding the connecting portion and the anode lead together by irradiating them with laser light, is featured by that the laser welding operation is performed in the state where a reflection plate having a slot and functioning to reflect reflected laser light is arranged between a weld portion of the connecting portion to be welded and the capacitor body while the anode lead is received in the slot.
Since, in this case, the laser welding operation is performed in the state where the reflection plate having the slot and functioning to reflect reflected laser light is arranged between the weld portion and the capacitor body while the anode lead is received in the slot, the reflection plate prevent irradiation of the capacitor body with reflected laser light, so that degradation of the capacitor body is prevented.
Consequently, it is possible to obtain a high quality chip type solid electrolytic capacitor.
A fabrication method for fabricating a chip type capacitor, according to a third aspect of the present invention, including the steps of mounting an anode lead extending from a capacitor body of a capacitor element on a connecting portion formed by bending up a portion of an anode terminal and welding a weld portion of the connecting portion and the anode lead together by irradiating them with laser light, is featured by that the laser welding operation is performed in the state where a reflection plate having a slot is arranged in a region between the weld portion and a capacitor body while the anode lead is received in the slot and the anode lead is urged to the connecting portion.
Since, in this case, the laser welding operation is performed in the state where the reflection plate having the slot is arranged in the region between weld portion and the capacitor body while the anode lead is received in the slot such that the anode lead is urged to the connecting portion, the bending and/or warping of the anode lead, which occurs when a plurality of capacitor bodies bonded to an aluminum holder are processed through respective fabrication steps and makes the contact of the anode leads with the connecting portions unstable, can be corrected and the welding operation can be performed in the state where the anode lead is always in firm contact with the connecting portion. As a result, degradation of bonding strength between the anode lead and the connecting portion can be avoided. Further, since the reflection plate prevents irradiation of the capacitor body with reflected laser light, degradation of the quality of the capacitor body is prevented.
Therefore, it is possible to obtain a high quality chip type solid electrolytic capacitor.
A fabrication method for fabricating a chip type capacitor, according to a fourth aspect of the present invention, relates to any one of the first to third aspects and is featured by that the connecting portion includes a welding notch for receiving the anode lead and welding side portions, which are formed on both sides of the welding notch and form a weld portion, and laser light irradiates only the weld portion.
Since, in this case, only the weld portion of the connecting portion is irradiated with laser light, the weld portion of the connecting portion is melted and the molten material flows around the anode lead in the welding notch, so that the bonding strength is stabilized and the utility of thereof is improved. Further, it becomes possible to restrict temperature rise of the anode lead to the irreducible minimum of the demand to thereby minimize temperature rise of the capacitor body of the capacitor element due to the temperature rise of the anode lead. Therefore, degradation of the quality of the capacitor body can be avoided.
Consequently, it becomes possible to obtain a higher quality chip type solid electrolytic capacitor.
A fabrication method for fabricating a chip type capacitor, according to a fifth aspect of the present invention, relates to any one of the first to third aspects of the present invention and is featured by that the connecting portion is irradiated with low energy density laser light and the anode lead is irradiated with high energy density laser light.
Since, in this case, the connecting portion is irradiated with low energy density laser light and the anode lead is irradiated with high energy density laser light, it is possible to desirably melt and bond the connecting portion and the anode lead, which have different melting points.
Therefore, it is possible to obtain a higher quality chip type solid electrolytic capacitor.
A fabrication apparatus for fabricating a chip type capacitor, according to a sixth aspect of the present invention in which an anode lead extending from a capacitor body of a capacitor element is mounted on a connecting portion, which is formed by bending up a portion of an anode terminal, and laser welding means welds the anode lead and the connecting portion together by laser light emitted therefrom, is featured by comprising pressing means for pressing the anode lead to the connecting portion in a region between a weld portion of the connecting portion and the capacitor body to thereby urge the anode lead to the connecting portion.
With this construction, it is possible to perform the laser light welding operation while the anode lead is urged to the connecting portion by the pressing means, so that it is possible to weld the anode lead to the connecting portion while the anode lead is in firm contact with the connecting piece. Therefore, degradation of bonding strength is prevented.
Consequently, it is possible to obtain a high quality chip type solid electrolytic capacitor.
Further, since the anode lead is pressed to the connecting portion in the region between the weld portion and the capacitor body, it is possible to improve the freedom of irradiating direction of laser light. In this case, the bending and/or warping of the anode lead, which occurs when a plurality of capacitor bodies bonded to an aluminum holder are processed through respective fabrication steps and makes the contact of the anode leads with the connecting portions unstable, can be corrected and the welding operation can be performed in the state where the anode lead is always in firm contact with the connecting portion.
A fabrication apparatus for fabricating a chip type capacitor, according to a seventh aspect of the present invention in which an anode lead extending from a capacitor body of a capacitor element is mounted on a connecting portion, which is formed by bending up a portion of an anode terminal, and laser welding means welds the anode lead and the connecting portion together by laser light emitted therefrom, is featured by comprising reflection plate arranging means for arranging a reflection plate having a slot in a region between a weld portion of the connecting portion to be laser-welded and the capacitor body, which are to be welded together by laser light, and functioning to reflect reflected laser light while the anode lead is fittingly received in the slot.
With this fabrication apparatus, the welding operation can be performed by the laser welding means in the state where the reflection plate is arranged in the region between the weld portion to be laser-welded and the capacitor body while the anode lead is received in the slot. Therefore, the reflection plate prevents irradiation of the capacitor body with reflected laser light, so that degradation of the capacitor body is prevented.
Consequently, it is possible to obtain a high quality chip type solid electrolytic capacitor.
A fabrication apparatus for fabricating a chip type capacitor, according to an eighth aspect of the present invention in which an anode lead extending from a capacitor body of a capacitor element is mounted on a connecting portion, which is formed by bending up a portion of an anode terminal, and laser welding means welds the anode lead and the connecting portion together by laser light emitted therefrom, is featured by comprising reflection plate arranging means for arranging a reflection plate having a slot in a region between a weld portion to be laser-welded and the capacitor body and functioning to reflect reflected laser light while the anode lead is fittingly received in the slot, wherein the reflection plate arranging means urges the anode lead to the connecting portion.
With this fabrication apparatus, since the reflection plate having the slot is arranged by the reflection plate arranging means in the region between the weld portion and the capacitor body while the anode lead is fittingly received in the slot to urge the anode lead to the connecting portion, the bending and/or warping of the anode lead, which occurs when a plurality of capacitor bodies bonded to an aluminum holder are processed through respective fabrication steps and makes the contact of the anode leads with the connecting portions unstable, can be corrected, the welding operation can be performed in the state where the anode lead is always in firm contact with the connecting portion. As a result, unstableness and degradation of the bonding strength can be avoided. Further, since the reflection plate prevents irradiation of the capacitor body of the capacitor element with reflected laser light, degradation of the quality of the capacitor body is prevented.
Consequently, it is possible to obtain a high quality chip type solid electrolytic capacitor.
A fabrication apparatus of a chip type capacitor, according to a ninth aspect of the present invention, relates to any one of the sixth to eighth aspects of the present invention and is featured by that the connecting portion includes a welding notch in which the anode lead is received and welding side portions formed on both sides of the welding notch and the laser welding means irradiates only the welding side portions with laser light.
Since the laser welding means irradiates only the welding side portions of the connecting portion with laser light, the welding side portions are melted and flow around the anode lead, so that the bonding strength is stabilized and the utility of thereof is improved. Further, it becomes possible to restrict temperature rise of the anode lead to the irreducible minimum of the demand to thereby minimize temperature rise of the capacitor body of the capacitor element due to the temperature rise of the anode lead. Therefore, degradation of the quality of the capacitor body can be avoided.
Consequently, it becomes possible to obtain a higher quality chip type solid electrolytic capacitor.
A fabrication apparatus of a chip type capacitor, according to a tenth aspect of the present invention, relates to any one of the sixth to eighth aspects of the present invention and is featured by that the laser welding means irradiates the connecting portion with low energy density laser light and the anode lead with high energy density laser light.
Since the laser welding means irradiates the connecting portion with low energy density laser light and the anode lead with high energy density laser light, it is possible to desirably melt and bond the connecting portion and the anode lead, which have different melting points.
Therefore, it is possible to obtain a higher quality chip type solid electrolytic capacitor.